A typical color silver halide photographic material comprises a flexible support with one or more coated layers on both sides, often referred to as an emulsion (imaging) side and the back (non-imaging) side. The back side generally has a conductive, antistatic layer and a scratch resistant top layer to facilitate film transport. The emulsion side generally has at least one layer sensitized to each of the three primary regions of the visible spectrum. They usually contain at least one blue-sensitive layer with a yellow image dye forming coupler, at least one green-sensitive layer with a magenta image dye forming coupler, and at least one red-sensitive layer with a cyan image dye forming coupler. Additional antihalation layers, interlayers, and a topcoat are usually also present on the emulsion side.
In general, it is desirable to reduce the thickness of coated layers as much as possible in photographic materials, especially the silver halide emulsion light-sensitive layers since they contain the most gelatin, silver halide emulsion grains, image coupler dispersion particles, and other photographic addenda. The image coupler dispersion particles generally also contain one or more high boiling, permanent organic coupler solvents as described for example in U.S. Pat. No. 2,322,027 (Jelley et al.).
Thinning of such layers can be achieved by reducing the amount of gelatin binders or by lowering the amount of other incorporated components, commonly known in the photographic industry as “junk”. Since gelatin is usually present as the binder for all of the other components in the layers, an important metric used to guide film formulators is the “gel to junk” ratio (or “gelatin-to-junk” ratio).
It can be useful to reduce coupler solvents to reduce gelatin coverage. One approach for doing this is to use specific yellow or magenta minimum density dyes as described for example in U.S. Pat. Nos. 7,629,112 (Zengerle et al.) and 7,632,632 (Zengerle et al.). In addition to reducing the cost of materials, thinning the light-sensitive layers is desirable for a number of reasons that are described in the prior art. For example, thinner layers can provide improved sharpness in the final photographic image due to reduced image scattering during exposure as described for example U.S. Pat. Nos. 5,891,613 (Zengerle et al.) and 6,544,724 (Satoh et al.). Reduction in the layer thickness can also lead to lower replenishment rates of processing solutions and an increase in development speed due to shorter diffusion paths throughout the multilayer structure of the imaged photographic material. Improved abrasion resistance can also be obtained with reduced coupler solvent levels in the cyan imaging layers as described in U.S. Pat. No. 7,223,529 (Zengerle et al.). The use of specific alcoholic coupler solvents to increase coupler reactivity (for example cyan coupler reactivity) in order to minimize coated levels of silver halide, image coupler dispersion particles, and gelatin to lower material costs in color print motion picture films is described for example in U.S. Pat. No. 7,153,640 (Zengerle et al.).
Since color motion picture print films are greatly magnified during their projection in theaters, it is important to avoid the dust and the generation of dirt during film manufacture and finishing operations as well as during handling and use in theaters. Undesired static charge build-up can occur when the films are transported on rewind equipment or through projectors. High static charges can attract dirt particles to the film surface. Debris generated during these operations that is deposited onto the film surfaces can cause defects that, if sufficiently large, can be seen on the projected film images. Thus, a great deal of work has been done in the industry to minimize dirt and dust generation of the back side of such films. In addition, efforts have been made to improve scratch resistance on the back side of the films, and to improve lubricity so that transport through projectors generates minimal dust.
Color motion picture print films having improved protective outer layers are described in U.S. Pat. No. 6,913,874 (Haller et al.). However, there is little description of efforts in the industry to minimize dirt and dust generation on the emulsion side of color motion picture print films.
It is desired to reduce the coated dry thickness of emulsion layers on the emulsion side of the color motion picture print films in order to reduce material costs, to increase the speed of development, and to reduce the replenishment rates of processing solutions. Since gelatin is a major component of such layers and contributor to layer thickness, it would be desirable to reduce the gelatin coverage in as many layers as possible. However, if too much gelatin is removed, dirt and dust generation increases during manufacturing, especially in film finishing during slitting and spooling operations. Thus, there is a need for a way to reduce the layer thickness while maintaining or lowering contamination from dust and dirt during manufacturing operations. It would also be desirable to provide color motion picture print films that enable more rapid development and reduced development replenishment rates, both of which will reduce the costs to the film processor and ultimately to the film user.